Synthesis of nitro-ketones



United States Pate US. Cl. 260-593 3 Claims ABSTRACT OF THE DISCLOSURE Nitroketones are prepared by treating homopolymers of propene and butene with nitrogen tetroxide. The resultant nitrated product is hydrolyzed to the nitroketone by heating in aqueous alkaline solution.

This is a division of application S.N. 379,339, filed June 30, 1964, now Patent No. 3,328,463.

This invention relates to aliphatic ketones. More particularly it relates to nitro-ketone alkanes, their preparation, their use as intermediates in the preparation of ashless lubricant additives, and lubricants containing such additives.

The operation of the present day internal combustion engines in automobiles, delivery trucks, taxicabs, police cars, etc. in so-called stop and go city use results in severe demands for high dispersancy and detergency as well as extreme oxidation stability and protection of metal parts to rust and corrosion. This severe demand on lubricant additives comes about by the accumulation of water and partial combustion products in the crankcase of the engines of the foregoing vehicles. Water and many of the partial combustion products result in sludge formation which deposits on the valve train, pistons, piston rings, oil screens and filters. The partial oxidation products, when deposited on hot metal surfaces, form varnishes which impair the efiicient operation of the engines. Many solutions to these severe performance demands of city driving conditions have been sought, but while solutions to the dispersing of water, sludge and varnish-forming materials in the lubricant oil was of paramount importance, it was also of paramount importance that the additives to accomplish the dispersing had to be thermally stable at high temperatures of continuous operation under high speed highway and expressway traveling. Also with the advent of the recommendation by internal combustion engine manufacturers of longer internals between draining and replacement of crankcase lubricants, emphasis has also been directed at the protection of bearings and other metal parts of the internal combustion engines against corrosion, rust and wear. To further complicate the problems of formulating crankcase lubricants for the increasingly severe service demanded by the improved internal combustion engines, there was the always present problem of compatibility of the other additives such as the anti-wear, anti-corrosion, anti-rust and anti-oxidation additives. By adjustment of ratios of various additive materials, compatibility could be achieved at the sacrifice of bearing wear or hearing corrosion, rust inhibition and even oxidation stability.

A new method has been discovered for the preparation of nitro-ketones from alkenes, which ketonesa re valuable intermediates in the preparation of oil-soluble derivatives that are useful as ashless lubricant additives.

In accordance with the present invention, an alkene is nitrated with nitrogen tetroxide under non-oxidizing conditions to form the corresponding nitro-nitrito alkane. The nitro-nitrito alkane is then hydrolyzed under alkaline ice conditions in the presence of a basic material non-reactive with said alkane to the corresponding nitro-ketone alkane.

The nitration of the alkene is eifected by treating the alkane under non-oxidizing conditions with nitrogen tetroxide in an inert carrier gas such as carbon dioxide or nitrogen at a temperature of from about 100 to about 250 F. until absorption of the nitrogen tetroxide ceases. The nitration is preferably conducted in an inert solvent. The amount of nitrogen tetroxide used will be about one mole per mole of unsaturation in the alkene. The nitrated product is substantially pure nitro-nitrito alkane.

Any olefinic material containing at least one ethylenically unsaturated site can be treated in accordance with the present invention. Monoand polyolefins can be converted to their corresponding nitro-ketones substantially quantitatively. Homopolymers of propane and butene having an average molecular weight in the range of from about 300 to 60,000 are especially useful products for the preparation of oil-soluble nitro-ketones that can be further reacted to form ashless lubricant additives.

The alkaline hydrolysis of the nitro-nitrito alkane can be effected by the addition of a concentrated aqueous solution of basic material non-reactive with the nitronitrito alkane thereto, and reacting the resultant mixture at reflux temperatures. Basic materials that can be used include quaternary ammonium hydroxides, polyamines that form quaternary ammonium hydroxides in situ such as diethylenetriamine, and inorganic bases such as barium hydroxide and calcium hydroxide. Temperatures may range from about 20 to about 150 C. for a period of time sufficient to convert the nitrito group to the keto group. Hydrolysis is generally complete when evolution of gas ceases.

The nitro-ketone alkanes containing at least 6 carbon atoms are particularly useful for conversion to ashless lubricant additives that impart detergency to liquid lubricating oils. A particular effective class of nitro-ketone alkanes are those derived from viscous polypropene and polybutene having an average molecular weight in the range of from about 300 to about 2,000.

Reaction of the nitro-ketone alkanes with a polyamine having the formula H N(RNH) H wherein R is C alkylene and x is l to 8, forms a nitro-Schifis Base condensation reaction product. Illustration of the polya-mines are ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, propylene diamine, butylene diamine, etc. The condensation of the nitroketone alkane and polyamine is conducted at temperatures of from about 200 to 320 F. in the presence a catalytic amount of an acid catalyst such as concentrated sulfuric acid. The molar proportion of the reactants is from about 2 to 4 moles of the alkane per mole of polyamine. The polyamine is preferably in slight excess to assure complete reaction with the keto groups in the nitro-ketone alkane.

The nitro-Schiffs Base condensation product is then borated with boric acid or boric anhydride using about 3 moles equivalent boric acid per mole of basic nitrogen in the condensation product to provide nitrogen to boron ratio of about 3:1. The boration is conducted at temperatures of from about 200 to 300 F. The borated condensation reaction product is a valuable lubricating oil detergent.

Illustrative of the invention are the following examples:

EXAMPLE I A viscous polybutene having an average molecular weight of about 860 was dissolved in heptane in a"3- necked flank equipped with a stirrer and gas distributor, and reflux condenser. To this solution nitrogen tetroxide was introduced in carbon dioxide carrier gas .at the rate of 2 cubic feet per hour at reflux temperatures, about 170 F., for a period of 16 hours. Infrared analysis of the reaction product indica'ted substantially complete conversion of the polybutene polymer to the corresponding nitro-nitrito alkane.

EXAMPLE II Basic hydrolysis of a portion of the nitro-nitrito reaction product of Example I was conducted by treating said product with an equimolar amount of a concentrated aqueous solution of calcium hydroxide at reflux temperatures for 4 hours. Infrared analysis of the resultant reaction product indicated substantially complete conversion of the nitro-nitrito product to the corresponding nitro-ketone.

EXAMPLE III To 450 grams of the nitration product of Example I was added a concentrated aqueous solution of 25 grams of diethylenetriamine. The resultant mixture was then reacted at reflux temperature for 3 hours. The resultant reaction mixture was separated on a silica gel column and a yield of 70 percent of the corresponding pure nitroketone was obtained.

EXAMPLE IV To 3 moles of the nitro-ketone product of Example II was added /3 mole of tetraethylenepentamine and 2 ml. of concentrated sulfuric acid as catalyst. The reaction mixture was then heated at 270 F. for 12 hours. There after, 200 grams of boric acid was added to the reaction mixture and the mixture heated at 300 F. for 12 hours. Analysis of the borated reaction product showed that it contained 1.27% nitrogen and 0.42% boron. Analysis of the condensation reaction product of the nitro-ketone and the amine by infrared showed the formation of the nitro- Schifis Base reaction product.

The herein described borated reaction products are particularly suitable for use in amounts of from about 0.1 to about 10 weight percent as ashless addition agents for lubricating oils.

EXAMPLE V Sludge 33 Varnish 38 Piston Varn. 7.2 Oil Ring Plugging 22 Oil Screen Plugging 5 This example illustrates that the borated products prepared in accordance with this invention exhibit excellent low temperature dispersency in lubricating oils.

Suitable lubricating base oils are hydrocarbon oils, e.g. petroleum oils, synthetic hydrocarbon lubricating oils such as those obtained by the polymerization of hydrocarbons, and other synthetic lubricating oils such as alkylene oxide type oils, for example, the Ucon Oils, polycarboxylic acid ester-type oils such as esters of adipic acid, sebacic acid, aselaic acid, etc. and other synthetic lubricating oils.

While this invention has been described in connection with the use of the herein described additives and lubricant compositions, their use is not limited thereto but the same can be used in products other than lubricating oils, such as for example, fuel oils, insulating oils, greases, non-drying animal and vegetable oils, waxes, and asphalts.

Concentrates of a suitable oil base containing more than 10%, e.g. from about 15% to about 50% or more, of the herein described derivatives, alone, or in combination with more than 10% of other additives, can be used for blending with other oils in proportions desired for the particular condition or use to give a finished product containing from about 0.1 to about 10 weight percent of the described derivative.

Lubricant composition containing the herein described derivatives can contain other addition agents such as for example, antioxidants, pour point depressors, V.I. improvers, etc.

I claim:

1. The method of forming n'itro-ketone derivatives of homopolymers of propene and butene which comprises (A) forming a nitrated homopolymer of propene or butene, said homopolymer having a molecular weight of about 300-60,000, by treating said homopolymer dis solved in an inert solvent with nitrogen tetroxide in an inert carrier gas at a temperature of about -250 F. until absorption of nitrogen tetroxide ceases; (B) adding water and a basic material nonreactive with said nitrated polymer to said solution containing said nitrated polymer, to form an aqueous alkaline hydrolysis mixture, the amount of said basic material being sufiicient to maintain said hydrolysis mixture alkaline during the heating step which follows; (C) heating said aqueous alkaline mixture at reflux temperature until the evolution of gas ceases; and (D) recovering from said aqueous reaction mixture the corresponding nitro-ketone derivative of said homopolymer.

'2. The method of claim 1 wherein said homopolymer is a polybutene having an average molecular weight of about 860, said inert gas is carbon dioxide, and said basic material is calcuim hydroxide.

3. The method of claim 1 wherein said homopolymer is a polybutene having an average molecular weight of about 860, said inert gas is carbon dioxide, and said basic material is diethylene diamine.

OTHER REFERENCES Levy et al. J. Chem. Soc. pp. 52-60 (1948).

LEON ZITVER, Primary Examiner.

M. M. JACOB, Assistant Examiner. 

